smythe



J. B. SMYTHE.

LIFTING JACK.

APPLICATION FILED FEB. 15. 1919.

1,393,734 Patented May 13, 1919.

3 SHEETS-SHEET I- J. B. SMYTHE.

LIFTING JACK;

APPLICATION FILED FEB.15, .919.

1,88,73%, Patented May 13, 1919.

3 SHEETSSHEET 2.

J. B. SMYTH LIFTING JACK.

APPLICATION FILED FEB. l5, 19x9.

Patented May 13, 1919.

3 SHEETSSHEET 3- Mama":

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specification of Letters Patent.

Application filed February 16, 1919. serial 151 a. 278,296.

To all whom it may concern:

Be it known that I, Josern B. Smyrna,-

a subject of the Kin of England, and a resi- Frovince of Quebec, Dominion of Canada, have invented certain new and useful Improvements in Lifting- Jacks, of which the following is a specification.

This invention relates to lifting jacks, and particularly to that class of jacks known as ratchet screw jacks.

Its object is to improve and perfect the type of quick action, self lowering jack described and claimed in Patent No. 1,131,286 issued to Joseph 0. St. Pierre, March 9, 1915, in which a supplemental train of spur gears were connected by ratchet mechanism to the main operating gear spindle, or shaft, so that they would be rotated by the latter when driven in a reverse direction to that taken by it in raising the 'ack.

In the above mentione patent, the high speed end of the train of gearing actuated a worm ear and worm, the threads of the latter belng so pitched that the jack would start the descent under its own load automatically when the brake is released.

lln the present invention the same worm and mechanism for actuating the same are used as is used in the jack described in the St. Pierre patent, but a new and improved manually operated brake mechanism is used I and interposed betweenthe brake mechanism and worm, a governor is provided which will control the speed of rotation of said Worm when the manually controlled mechanism is not in operation, said governor preventing the Worm from rotating beyond a predeteripined speed during the lowering of the ac v J The invention consists in certain novel features of construction and arrangement of parts which will be readily understood by reference to the description of the drawings and to the claims to be hereinafter given.

For the purpose of illustrating the invention, one preferred form thereof is illustrated inthe drawings, this form having been found to give satisfactory and reliable results, although it is to be understood that the various instrumentalities of which the invention consists can be variously arranged and organized, and'that the invention is not limited to the recise arrangement and er ganization of t e instrumentalities as herein shown and described, except as required by the scope of theappenoled claims.

Of t e drawingsz' Figure 1 represents a horizontal section ofa lifting jack embodying the features of t h1s invention, the cutting plane being on line 1, 1, on Flg. 2.

Fig. 2 represents a vertical section'of. the same on l1ne 2,2, on Fig. 1.

Flg. 3 represents an enlarged vertical sec 131011 011 line 3, 3, on Fig. 2.

Flg. 4: represents an elevation f the governor. ii

Fig. 5 represents a plan view ofthh same.

F1 6 represents a section on line 6, 6, on Fig. 3, and

Fig. 7 represents a section on line 7, '2, on Fig. 3.

Similar characters indicate like throughout the several figures of the rawmgs.

In the drawings, 10 represents asuitable base supporting a stationary standard 11 over the outer periphery of which is fitted a movable sleeve 12, to the 11 per end of which is threaded a cap 13. l n the upper end of the standard 11 is mounted a nut 14;- to which is threaded a lifting screw 15 hav ing splined to its upper reduced' end a gear 16 with which meshes a gear 17 formed upon or secured to a revoluble shaft or spindle 18, the outer end of which is'provided with a plurality of spring pressed pawls 23 piv-' otally secured to a spur gear 24 freely revoluble and mounted upon a reduced portion 25 of the cylindrical hub 26 forming a hearing for said spindle or shaft 18. Thishub 26 is formed integral with a removable plate 27 secured to the flanged projection 28 forming a part of the movable member 12. The gear 24 meshes with a pinion 29 secured to or formed integral with a revoluble member 30 to which is also secured arts Patented May 116, 31816.

a gear .31 meshing with a pinion 32 formed upon or secured to a revoluble member 33 to which is also secured a worm gear 34. This worm gear 34 meshes with a worm 35 secured upon a shaft 36 and interposed between the lugs 37 secured the plate 27 and in which said shaft 36 is provided with bearin s. The pitch of the worm 35 is such that uring the rotation of the worm gear 34 rotary movement will be imparted to the shaft 36. This shaft 36 has secured to its outer end a friction disk 38 as indicated in Fig. 3 of the drawin s and is adapted to have friction applled thereto by means of the friction members 39 pivoted to the lug 40 extending inwardly from the cover plate 27.

The lug 40 is provided 1n a side face thereof with a cylindrical chamber 41 wh1ch is closed by the friction disk 38,

The rear face of the friction disk 38 has projecting therefrom the headed members 42 acting as guides for the shdmg members 43, each member 43 having a slot 44 therein through which extends the shank of one of the members 42. I

The disk 38 has also projecting therefrom, the pivot pins 45 on which the weighted levers 46 are mounted, one end of each of said levers being bifurcated and provided with a pin 47 extending through a slidable member 43.

One end 48 of each member 43 is provided with a friction surface adapted toengage the cylindrical wall of the chamber 41 when the rotation of the disk 38 exceeds a predetermined speed and by centrifugal force causes the weights to be thrown outwardly. I The friction surfaces on the ends 48 are separated normally from the wall of chambers 41 by the springs 50 interposed between the opposite ends of said slidable members 43 and the fixed pin-s 51 mounted on said disk 38.

The brake members 39 are pivotally mounted on the studs 52 the shanks of which extend through the lug 40 and have nuts 53 threaded to their inner ends.

The lower ends 54 of the brake members 39 are curved to fit the periphery of the disk 38 as indicated in Fig. 6, and are normally held in frictional contact therewith by means of the spring 55.

Each brake member 39 is provided near its upper end with a lateral projection 56, said projections extending into parallel slots 57 in an oscillating disk 58 mounted in a cylindrical hole 59 in the side wall ofthe extension 28.

The disk 58 is held in position by the bolt, or stud, 60, the reduced threaded shank of which is secured in the lug 40.

The disk 58 is provided with a finger pad 61 by which the said disk may be moved about said bolt, or stud, 60 thereby moving the slots 57 into a osition nearer vertical and thus acting on t 0 pins 56 to move them toward each other.

This operation will cause the brake members 39 to be moved about their pivots and cause a separation of the curved ends 54 from the periphery of the disk 58.

When the friction of the brake-members 39 is removed from the disk 38, the jack is free to lower under its load.

Should the jack under an excessive load rotate the worm 35 at too great a speed for safety, the weights 49 will move outwardly and force the friction surfaces of the ends 48 into frictional contact with the cylindrical wall of the chamber 41 and thereby retard the speed of the worm shaft 36 to which the governor disk 38 is secured. i

As soon as pressure is removed from the pad, or arm 61, the spring 55 will immediately force the ends 54 of the brake members 39 into frictional contact with the disk 58 and prevent any further lowering of the jack.

In the operation of the device when it is desired to raise the movable member 12, the operating mechanism 19 is manipulated to turn the spindle 18 and gear 17 formed thereon in the direction of thearrow a on Fig. 3 of the drawings. When this is-done, the ratchet 22* will freely pass the pawls 23 Without disturbing the train of gearing adapted during the lowering of the jack to be actuated by the driving gear 24 to which the pawls 23 are pivotally secured. During this operation, the friction member 39 is in contact with the friction disk 38. It is obvious, therefore, that during the operation of the jack to lift a load, the operating mechanism 19 will act directly upon the movable member 12 through the gears 17 and 16 and screw 15 without afiecting in any manner the operation of the train of gearing hereinbefore mentioned.

Then the weight has been lifted sufficiently it will be retained in its elevated o-sition as the friction member 39 is held 1n frictional contact with the rotatable member 38 and consequently all movement of the said train of gears will be effectually prevented thereby resisting the tendency of said load to actuate this train by the rotation of the spindle 18 in a direction opposite to that indicated by the arrow (1 on Fig. 3, thereby causing the engagement of the teeth of the ratchet wheel 22 and the pawls 23. When it isv desired to lower the movable member 12, the friction member 39 may be removed from the rotatable member 38 by pressing on the arm 61 and with the pawls 23 in engagement with the teeth of the ratchet 22*, the train of gearing will be driven by the rotation of the gear 17 and its spindle 18. threads are such as to permit the jack to The pitch of the worm I start automaticall' to descend under-its own load when its br e is released. This train of gearin is geared up to such an extent that the s aft 36 and thea'ot'atable member 38 rotate very rapidly, while the inertia of the gearing acts to substantially retard and prevent excessive .speed in the descent of the jack. Should an excessive load be upon the cap 13 so that the member 12 moves downwardly too rapidly, its movement may be arrested by the action of the governor. If it is desired to entirely stop the lowering of the jack, pressure is removed from pad 61 and the brake members 39 will be forced into contact with disk 38.

The multiplication of the braking power through the high ratio gearing and through the worm and worm Wheel will serve to make possible the quick and easy stoppage by a light pressure of the brake, of the descending jack at any point.

It is quite obvious that when this friction member 39 is in contact with the rotatable member 38, the rotation of the spindle 18 will be controlled during the lowering of the jack through a train of gearing or may be arrestedlr completely while during the lifting operation, these mechanisms are entirely unaffected by the rotation 'of said spindle 18.

1 It is obvious that when the friction brake disk 38 has'reached a certain predetermined speed, the weighted ends 39 of the levers 46 will swing outwardly by centrifugal force 'and cause the members 43 to advance and press against the cylindrical wall of the chamber 41 thereby retarding the speed of said disk 38. This retarding action balances the load that is being lowered, a heavy load causing more speed and more power exerted by the governor.

Owing to the use of the governor, the accumulation of excessive speed of the friction disk is prevented. and consequently it obviates any injury to said disk or the manually actuated brake members coacting therewith when stopping the descent of the loaded jaEk.

Without the governor, the disk 38 will attain such an accumulation of speed as to cause intense heat and consequent wear when the brake members 39 are applied to stop the descent of the load after considerable downward travel.

With jacks of this character in use, when an engine or other heavy machine is jacked up on both sides, the machine may be lowered evenly since the speed of both jacks will be the same.

It is self-evident that with the mechanism described, an acidental lowering of the jack is wholly obviated and whenever it becomes necessary to lower the jack quickly, it may be acomplished with any degree of rapidity desired.

drivin It is believed that the operation and many advantages of the invention will be fully understood from the foregoing description.

Having thus described my invention, ll c1aim-' *1. The combination of an o crating shaft; a ratchet revoluble with sai shaft; a ear loosely mounted on said shaft; a paw on said gear engaging said ratchet; a worm mechanism for said worm actuated by sai gear; a fixed member rovided with a cylindrical chamber; a cylin rical disk rotated by said worm; a brake member coaeting with said disk; manually actuated means for controlling said brake member; and weight actuated members carried by said disk and adapted to be moved into frictional contact with the wall of said chamber when said disk is rotated at a predetermined speed.

2. The combination of an operating shaft; a ratchet revoluble with said shaft; a gear loosely mounted on said shaft; a pawl on said gear engaging said ratchet; a Worm: driving mechanism for said worm actuated by said gear; a fixed member provided with a cylindrical chamber; a cylindrical disk rotated by said worm; a ivoted brake member coacting with said dis manually actuated means or controlling said brake member; and wei ht actuated members carried by said disk and adapted to be moved into frictional contact with the wall of said chamber when said disk is rotated at a predetermined speed.

3. The combination of an o crating shaft; a ratchet revoluble with sai shaft; a gear 100 loosely mounted on said shaft; a pawl on said gear engaging said ratchet; a worm; drivin mechanism for said worm actuated by sai gear; a fixed member provided with a cylindrical chamber; a cylindrical disk ro- 106 tated by said worm; two brake members normally in frictional contact with the periphery of said disk; manually actuated means for moving said brake members from contact with said disk; and weight actuated 110 members carried by said disk and adapted to be moved into frictional contact with the wall of said chamber when said disk is rotated at a predetermined speed.

4. The combination of an operating shaft; 115 a ratchet revoluble with said shaft; a gear loosely mounted on said shaft; a pawl on said gear engaging said ratchet; a worm; drivin mechanism for said worm actuated by sai gear; a fixed member provided with 120 a cylindrical chamber; a cylindrical disk rotated by said worm; weight actuated members carried by said disk and adapted to be moved into frictional contact with the wall of said chamber when said disk is rotated at 125 a predetermined speed; and braking means coacting With'said disk.

V 5. The combination of an operating shaft;

a ratchet revoluble with said shaft; a'gear loosely mounted on said shaft; a pawl on we .a cylindrical chamber said gear engaging said ratchet; a worm drivin mechanism for said worm actuated by sai gear; a fixed inember provided with 4 a cylindrical disk rotated by said worm; friction members movably mounted on said disk; pivoted weighted members adapted to move said friction memhere into contact with the wall of said chamber when said disk is rotated at a predetermined speed; and braking means coacting with said disk.

6. The combination of an operating shaft; a ratchet revoluble with said shaft; a' car loosely mounted on said shaft; a paw on.

said gear engaging said ratchet; a worm; drivin mechanism for said worm actuated by sai gear; a fixed member rovided with a cylindrical chamber; a cylin rical disk rotated by said worm; friction members slidably mounted on said disk; pivoted weighted members adapted to move said friction members into contact with the .Wall of said chamber when said disk is rotated at a predetermined speed; and braking means coacting with said disk.

mosses f v 7 The combination of an o aerating shaft; a ratchet revoluble with sai shaft; a ear loosely mounted on said shaft; a paw on said gear engaging said ratchet; a worm" means for controlling saidbrake member;

and weight actuated members carried by said disk and ada ted to be moved into frictional contact with the wall of said chamber when said disk is rotated at a predetermine speed.

Boston, Mass, this 1st day of February,

JOSEPH B. SMYTHE. -Witnesses:

WALTER E. LOMBARD, NATHAN C. LOMBARD.

Signed by me a a Post Oat Square, 

